Have a tough time using this outdoors if theres any type of breeze blowing. The app tells me that theres too much motion going on so wont take a reading. If the phone is moving at all then you will not be able to get a reading. So its not that often that I can go out on the field and bot have some type of breeze that will disrupt the phone.
Its very hard to read the screen on the iPhone after a ball goes by. The brightness of the readout numbers between the background is not very good. The best thing to do is link between two smart phones so you can have the reading in your hand as seen the ads instead of trying to read the one thats on the ground.
Hellsredsled about Athla Velocity